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Superconducting Fault Current Limiters A. V. Velichko, T. A. Coombs Department of Engineering, Cambridge University, UK. Funded by EPSRC. Outline. Overview of the work done Physical Background and Modelling Simulation and Experiment Summary and Future Plans. Overview. - PowerPoint PPT Presentation
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The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 1
Superconducting Fault
Current Limiters A. V. Velichko, T. A. Coombs
Department of Engineering, Cambridge University, UK.
Funded by EPSRC
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 2
Outline
Overview of the work done Physical Background and Modelling Simulation and Experiment Summary and Future Plans
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 3
Overview
FCLs are highly nonlinear devices, extensive simulation is required:
So far we have addressed:- High-aspect ratio - Multi-element configuration- First Experiments (DC VACH, AC loss and Pulse Measurements)
Problems remaining to solve:- Structural deformations (simulation and experiment) - Overall contribution to the power network.
Problems to be solved within the project:
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 4
Physical Background and Modelling (I)
SingleFCL
Structural
ThermalElectrical
All Properties are NONLINEAR
and INTERDEPENDENT!
If done consistently & simultaneously –
very time-consuming and could be fallible
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 5
Physical Background and Modelling (II)
EXISTING PROPRIETARY MODEL
From Experiment: - Spread in Ic and n; Strain and Stress;
Model takes into account:Thermal and Electrical;
Need to incorporate: Structural, Multi-element
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 6
Physical Background and Modelling (III)
• 3D model• Accounts for Inhomogeneities • Proper thermal boundary conditions• Linked Electrical and Thermal Properties• External Elements
Nitrogen boil-off
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 7
Simulation (I)
We also use commercial FEM software (FEMLAB) to:
- Verify the proprietary model- Simulate other features (Structural modelling)- Quick test for new geometries
So far we have used Femlab to:
• Verify T and I –distribution for metals • Estimate importance of metallic substrate• Check the concept of the length scaling
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 8
Simulation: verifying our model (II)FCLSimu2003D & FEMLAB
Cu-block, 1*0.5*0.25 mm3, takes ~ 1 minute on P-IV, 2.4 GHz, 512 MGb RAM
T = 275.24-275.3 K T = 260.24-260.27 K
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 9
Simulation: effect of substrate (III)
Ni (5-50 m)-CeO2(0.5 m)-YBCO(1.0 m)-Ag (10 m) over 1 sec, Q=10*(1+2*t), (2D, 3554 cells, 372 boundary elements)
Multilayer Ni/CeO2/YBCO/Ag, ~ 2 minutes on P-IV, 2.4 GHz, 512 MGb RAM
Ni-5m Ni-25m Ni-50m
FCLSimu2003D
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 10
Simulation: size-multipliers (IV)
T = 266.62-266.64 KScaled Up by 10
T = 266.67-266.68 K
Unscaled, Cu, 1*0.5*0.1 mm3
T = 265.5-267.5 K
Scaled Down by 10
FCLSimu2003D
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 11
Simulation: size-multipliers (V)
BSCCO, Unscaled,6*5*0.5 mm3
BSCCO, Scaled Up by 1000 to 6*5*0.5 mm3
BSCCO, Scaled down by 0.001 to 6*5*0.5 mm3
T = 80.8-81.9 K T = 80.8-81.9 K T = 80.8-81.9 K
FCLSimu2003D
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 12
Simulation: multi-element (VI)FCLSimu2003D
Two uniform elements in parallel, YBCO, 200*40*25 m3 each
YBCO: T = 150.1-150.7 K
N-gas
YBCO
YBCO
Layout
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 13
Simulation: multi-element + defect (VII)
Two elements in parallel, one with defect YBCO, 200*40*25 m3 each
YBCO: T = 106.7-106.8 K
N-gas
YBCO
YBCO
YBCO: T = 175.1-176.1 K
Layout
FCLSimu2003D
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 14
Experiments – DC VACH (I)
dc Current-Voltage characteristics,4 consecutive runs
YBCO tape, dc IV-characteristics, 7/03/2006
I, A
0 20 40 60 80 100 120 140 160
U,
V
0.0
5.0e-6
1.0e-5
1.5e-5
2.0e-5
2.5e-5
1st run2nd run3rd run4th run
DC in-phase Voltage vs. Current for LANL YBCO tape No.1, 7.03.06
I, A
0 20 40 60 80 100 120 140 160
DC
Vo
ltag
e (V
)
-5.0e-6
0.0
5.0e-6
1.0e-5
1.5e-5
2.0e-5
2.5e-5
Vc*(I/Ic)^nVdc
Fitting dc Current-Voltage Characteristic with EJ-model
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 15
Experiments, AC Pulses (II)
AC Pulse measurements, 25% Vmains
Pulse measurements (2 pulses, 25% V_mains) on YBCO tape No.1, 7.03.06
time, sec
0.07 0.08 0.09 0.10 0.11 0.12
I ac, A
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
Ua
c, V
-0.04
-0.02
0.00
0.02
0.04CurrentVoltage
Pulse measurements (2 pulses, 30% V_mains) on YBCO tape No.1, 7.03.06
time, sec
0.07 0.08 0.09 0.10 0.11 0.12
Ia
c,
A
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
Ua
c, V
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
0.10
CurrentVoltage
AC Pulse measurements, 30% Vmains
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 16
Experiments, AC Pulses (III)
AC Pulse measurements, 6 pulses45% Vmains, expanded
Pulse measurements (2 pulses, 45% V_mains) on YBCO tape
time, sec
0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
Ia
c,
A
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
Ua
c,
V
-3
-2
-1
0
1
2
3
CurrentVoltage
Pulse measurements (2 pulses, 45% V_mains) on YBCO tape, expanded
time, sec
0.04 0.05 0.06 0.07 0.08
I ac, A
-0.10
-0.05
0.00
0.05
0.10
Ua
c, V
-2
-1
0
1
2
CurrentVoltage
AC Pulse measurements, 6 pulses45% Vmains, full scale
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 17
Summary and Future Plans
So far we have:• Estimated Substrate effect• Verified proprietary software in FEMLAB• Solved high-aspect ratio problem• Attempted simulation of multi-element geometry• Performed first experiments: DC, AC loss & pulse
In the near future we plan to:• Input realistic parameters (n and Jc) into the EJ-model• Continue with multi-element model (target - YBCO tape)• Simulate Structural Modifications• Complete Electrical Network• Further experiments: IV-characteristics, stress & strain
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 18
Project Schedule (original)Activity Year 1 Year 2 Year 3
Multi-Element Model
Structural Failure
Modelling of Complete Electrical System
Measurement
Validation
Project months 3 6 9 15 18 21 27 30 33
Mastered existing FCL modelCreated 2D Thermal model in FEMLAB
Repeat Existing model in Femlab & Built multi-element model
Setting up Experiments & Making Measurements
Building Structural Model
The EPEC Superconductivity Group –Engineering Department - University of Cambridge www2.eng.cam.ac.uk/~tac1000 19
Project Schedule (reviewed)Activity Year 1 Year 2 Year 3
Multi-Element Model
Structural Failure
Modelling of Complete Electrical System
Measurement
Validation
Project months 3 6 9 15 18 21 27 30 33
Estimated Substrate effectSolved high aspect-ratio problemVerified Existing model in Femlab & Built multi-element model
Setting up Experiments& Making Measurements
Building & verifying Structural Model
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